1. Field of the Invention
Embodiments of the invention generally relate to heater baskets for use in rotary regenerative air preheaters, and more particularly to an improved lifting system for use with low profile heater baskets.
2. Discussion of Related Art
Rotary regenerative air preheaters use heat transfer surfaces called heating elements that are packed into baskets for easy handling and removal. Low profile baskets, such as the basket 1 shown in FIG. 1, are used when it is desired to maximize the profile height of the heating elements in order to maximize the thermal performance of the air preheater and where there is a restriction in available height due, for example, to the existing dimensions of the regenerative heater's rotor/stator, where the new heating elements baskets are to be installed.
The configuration of the low profile basket 1 minimizes the total height of the basket's side grids 2, which maximizes the height of the heating elements while maintaining the same basket outer dimensions. In this particular type of basket, the lifting lugs 4 are positioned at the corners 6 of the basket 1, since it is feasible to use the side grids 2 to lift the basket 1.
Previous lifting lugs 4 consisted of flat plates cut to conform to the inner shape of the basket angles. These flat plates were welded to the corner of the basket, and included a threaded hole 8 for engaging a threaded eyebolt 10 which, in turn, was coupled to a set of steel chain/wire rope slings 12 used as standard lifting equipment.
Such prior arrangements suffer from the problem that over time, they degrade and must be rethreaded. For example, the repeated insertion and removal of the threaded eyebolt 10 can cause wear on the threads of the threaded hole 8. Seizing of the threads, misthreading, and stripping of threads is also a problem which can require costly repair from both a material and time standpoint. In addition, the threads and plates are subject to corrosion, which can also cause problems with proper installation and engagement of the threaded eyebolt. Thus, there is a need for an improved lifting arrangement for low profile heater baskets.